Rosie and Ruby Formosa, who were born joined at the abdomen and shared part of the intestine, needed an emergency operation to separate them.

The identical twins, who are only 12 weeks old, underwent an operation at London's Great Ormond Street hospital (GOSH) on 27 July, the day after they were born.

Despite being told that survival chances were low, the sisters are now doing well and are smiling "bubbly babies", their mother Angela Formosa said.

Formosa, from Bexleyheath, Kent, said she had a "textbook" pregnancy with her first daughter Lily, now aged five, so finding out the twins were joined was a shock.

"At an early pregnancy scan they said the twins looked very close together so I went to King's College for another scan," the 32-year-old said.

"Between 16 and 20 weeks we found out that they were joined – I didn't know what to think, I was shocked and I felt sad.

"We didn't know what to expect until they were born. The doctors could not tell where they were connected.

"They decided to deliver them early at 34 weeks. I went into University College Hospital and had the C-section and the doctors decided that the girls should go for their operation quite soon, within a couple of hours they had been taken to GOSH."

The girls were operated on the next day by a team of specialists led by paediatric surgeon Professor Agostino Pierro.

"In this case, the twins were joined by the abdomen at the level of the umbilicus and shared part of the intestine," he said.

"The operation to separate the twins had to be performed as an emergency because of an intestinal blockage.